Various solders and glasses have been used as an adhesive material and a sealing material of electronic components until now. In particular, gold-tin solder and lead glass have been used because there is a case where heat-resistance of parts of a semiconductor package, a crystal unit, a MEMS, etc. is low that is approximately 400° C. Materials used for them are required, according to their use, to have various characteristics such as chemical durability, mechanical strength, fluidity, etc. In particular, in case of using them as the sealing material, fluidity at a low temperature is mentioned as an important factor.
In case that the above-mentioned fluidity is insufficient, it is not possible to obtain the characteristics required in each electronic component because there is a risk of leaking out from a sealed part. In Patent Publication 1, the gold-tin solder is used for manufacturing a piezoelectric vibrator incorporating a crystal unit, and sealing at 250° C. to 500° C. is disclosed. On the other hand, gold-tin solder is high-priced and lead glass contains a large amount of PbO which has a heavy burden on a human body and on the environment. Therefore, an alternative material has been required.
As the above alternative material, for example, Patent Publication 2 proposes a V2O5—TeO2—BaO—ZnO glass as a glass having a low softening point. The publication discloses a glass having four components such as 16-80 wt % of V2O5, 0-60 wt % of TeO2, 4-50 wt % of BaO, and 0-40 wt % of ZnO, or a glass where a lead-free low softening point glass, which is composed of 40-80 wt % of V2O5, 0-40 wt % of ZnO, and 10-50 wt % of BaO, is calculated as 100 pts·wt, and where 1-60 pts·wt of TeO2 is added to 100 pts·wt of the three components, thereby is prepared. Furthermore, examples in the publication show that softening points the glasses have are 310-320° C. In the publication, there is description of the fact that “fluidity” is good, but there is no description about the actual evaluation method. Therefore, detailed degree of the fluidity is unknown.
Furthermore, Patent Publication 3 proposes low softening point glasses which are a V2O5—TeO2—WO3—P2O5 glass and a V2O5—TeO2—WO3—ZnO glass. In the above V2O5—TeO2—WO3—P2O5 glass, its fluidity is rather insufficient, and there seem to be an increase of its softening point as P2O5 is contained. Furthermore, in the above V2O5—TeO2—WO3—ZnO glass, the glass shows excellent fluidity, and its softening point is in a range of 335 to 383° C. in the examples where BaO component is added into the above essential components.